The science encyclopedia reviews and explains a certain field of science or objects in that field of science. The purpose of this genre of books is to explain and record scientific observations and properties. They are resource books which can be reffered to or used to refresh one's mind of a scientific property or concept. 48 out of 50 people do not possess scientific encyclopedias, but 9 out of 10 people who do own them say the are very useful in almost any aspect of home education.